In my co-pending application, as depicted in FIG. 1 and 2 herein for ease of explanation, there is disclosed a belt scraping apparatus 10 including a cylinder 12 in sealing contact with upper and lower end caps 14 and 16 sealed to ends of the cylinder with plural tension rods 18 each applying a predetermined tightening force to the end caps by conventional heads or nuts 20 and 22, respectively. The lower end cap 16 may be provided with two openings or ports 24 and 26 formed to receive known types of fittings. One of these openings or ports 26 is connected to a pressurized water source 27 through a hose 27a and an optional pressure regulating device 27b to admit pressurized water into the lower end of cylinder 12 where it acts on a piston head of a single acting type slidably contained within the cylinder.
The pressurized water source, in a mining environment for example and as in the present invention, is preferably a conventional pumping station P that generally comprises an available source of water supplied by a pump located outside the mine through the hose 27b to the mining site at a pressure generally between 45-300 psi. This pressurized water is conventionally used for cleaning of equipment, and as a means for fighting fires within the mine. In accordance with the invention described in my co-pending application, the piston within the cylinder is of a single acting type in that the piston is moved to and maintained at the upper end of the cylinder under the action of pressurized water to maintain the belt scraper described more fully below in contact with the conveyor belt until such time as the supply of pressurized water into the lower end of the cylinder is shut off via the pressure regulating device. The other opening 24 is for connection to a pressure release mechanism (optional and not shown) and preferably a pressure gauge. A closeable fitting 28 in the upper end cap 14 allows drainage of any pressurized water that may leak past the piston head contained within the cylinder 12 during use.
The pressurized water cylinder assembly described above, in accordance with my co-pending application, is mounted by an attachment fork 30 (secured to the bottom of end cap 16) to a base 36 via rotatable connection to a trunnion 34 with pin 32. The piston is connected to a connecting rod 38 sealingly and slidably guided through upper end cap 14. Rod 38 is moveable in opposite directions indicated by arrow A in a direction parallel to the cylinder axis. The cylinder 12, the piston therewithin, end caps 14 and 16, are preferably made up of materials which are not corroded by the pressurized water, such as fiber glass, acrylic plastics, or reinforced composites that are readily lubricated by water without the need for externally provided lubrication.
The upper end of connecting rod 38 supports a fork element 42 rotatably pinned to a lever arm 44 rigidly connected to a shaft 46 rotatably supported in a pair of bearings 48.
A plurality of through holes 43 are distributed along the length of arm 44 for selective engagement of pin 42 therethrough, which persons skilled in the mechanical arts will immediately appreciate as a means to discretely adjust the moment arm at which the connecting rod force is applied about the axis of shaft 46.
Rigidly attached to a portion of shaft 46 between supporting journal bearing elements 48 is a transverse element 50 at a distal end of which is attached a scraper blade element 52 having a scraping edge 54. As is indicated in phantom lines in FIG. 1, a cylinder 56 of circular cross-section is conventionally used to support and guide thereover an approaching length 58 of a moving belt which passes over the cylindrical outer surface of cylinder 56 and returns for reloading as a moving length 62 of the belt. Naturally, the scraper blade element 52 must be so positioned vis-a-vis cylinder 56 and the moving belt as to be itself movable into controlled scraping contact with moving belt length 62, as best understood with reference to FIG. 2.
Although considerable adjustment of the applied moment to rotate shaft 46 is obtained by selecting one of the plurality of through holes 43 in arm 44 for a given position of base 36, even further adjustment may be obtained by relocating attachment means 64, e.g., conventional nuts and bolts into any of paired apertures 65 in a fixed support element 66 that stays in place vis-a-vis the conveyor belt structure. Given the structure described hitherto, it is easy for a user, simply by loosening a few bolts and nuts such as 64 and/or repositioning pin 42 in any of apertures 43, to very quickly and securely adjust a component of the force providable by connecting rod 38 and the moment arm at which such a force is applied to generate a useful torque about the axis of shaft 46. There is, thus, provided in the present invention a very easily adjustable means for discretely controlling the force with which scraper blade element 52 can be applied to a length 62 of a moving belt to scrape the same. Note that the adjustment so described is in addition to and complementary of any adjustment that may be obtained by regulating the pressure of the pressurized water actuating the piston within cylinder 12.
In practice, therefore, once the user using his judgment and experience decides exactly which holes 43 and 65 to use to locate the cylinder assembly 10, he or she will set a pressure regulator of known type to limit the pressure of pressurized water that may enter cylinder 12 to a maximum value, thereby ensuring that a desired factor of safety is obtained to avoid accidental rupture of cylinder 12. He or she then operates whatever controls are necessary, e.g., a valve, to provide pressurized water to cylinder 12 to generate an outward motion of connecting rod 38 vis-a-vis cylinder 12, so that a force is applied as indicated by arrow "A" in a direction normal to arm 44. This will cause shaft 46 and the attached scraper blade assembly to rotate clockwise as illustrated in FIG. 1.
The scraper blade assembly therefore moves in an arcuate path, as indicated by the curved arrow B, toward contact with the belt 58 passing over the outer surface of cylinder 56. Upon sufficient movement of blade element 52, the scraping edge 54 thereof will move as indicated by the arrows C into scraping contact along a line 60 (parallel to the axis of shaft 46) so that substantially the entire length of blade edge 54 is controllably pressed against the outer surface of turning moving length 62 of the conveyor belt. For most applications it may be most convenient to ensure that this line of contact 60 is located so that scraper blade edge 54 presses on the conveyor belt in a manner resisted by the outer surface of cylinder 56.
While the foregoing apparatus 10 of my co-pending application provides a highly desirable belt scraping action in a manner using pressurized water that is entirely safe and compatible with the use of equipment in sensitive locations without increasing any operational hazards, the following problems noted. First, since the scraper blade 52 is formed of the same material extending continuously for substantially the full width of the belt, the blade tends to wear unevenly since most of the material conveyed along the upper run of the belt gathers at the center longitudinally extending portion thereof, exerting greater abrasive contact against the center part of the scraper than at the edge portions of the scraper located adjacent the center part. Thereby, the belt scraper wears unevenly and eventually assumes a curved concave configuration with minimal if any scraping contact between the center portion of the scraper and the center of the belt where scraping is particularly necessary.
In my blade scraper mechanism of the aforesaid co-pending application, the scraping blade is of one piece extending transversely the full width of the conveyor belt. Replacement of the scraper blade necessitates removal of the entire blade element as well as the shaft 46 from its journal supports 48.
It is accordingly one object of the present invention to provide a scraper element for a belt scraper mechanism that wears evenly along the entire length of the scraper.
Another object of the invention is to easily detach the scraper element from the scraper mechanism for ease of replacement or repair.
Still another object of the invention is to form the scraper from individual scraper units easily detachably mounted to the scraper mechanism to form a continuous edge extending the full width of the belt.
Another object of the invention is to detachably mount the individual scraper units without requiring removal or manipulation of the blade scraper unit support shaft assembly from the conveyor.
Still another object is to provide a belt scraper mechanism wherein the individually mounted belt scraper units are of different hardness along the width of the conveyor belt to insure even wear of the belt scraper units across the entire belt width.
Yet a further object is to form the at least one or more individual belt scraper units mounted to contact the center portion of the belt where the most abrasive conditions occur of a material having a greater hardness than belt scraper units mounted to contact lateral or side portions of the belt where less abrasive conditions occur due to a smaller amount of abrasive material on the conveyor belt in comparison with greater amounts of abrasive material conveyed on center portions of the belt.
During belt scraping action, the belt scraper is subject to wear and must eventually replaced. However, as a result of scraping, the belt scraping element becomes coated with dirty and gritty material scraped from the belt, rendering it difficult if not impossible to visually monitor the belt scraper element to determine when replacement is necessary.
Still another object of the present invention is to provide a means for visually detecting the extent of wear of the belt scraper elements to determine when replacement becomes necessary.
Another object of the invention is to determine when replacement of the belt scraper units becomes necessary by monitoring the degree to which the piston head moves during belt scraping operation as a function of further extension of the piston connecting rod which occurs as the belt scraper wears and which is proportional to the extent of incremental wear.
Yet a further object is to monitor movement of the piston head as a function of wear of the belt scrapers by visually marking reference locations on a transparent cylinder carrying the piston head to temporarily halt belt scraping operations for replacement of one or more of the belt scraper units when the piston head travels along the cylinder to a position adjacent one of the reference marks.
In my aforesaid co-pending application, the belt scraping element is depicted in contact with the belt as it passes around the conveyor end roll. While this a commonly accepted mounting arrangement for the scrapers, the belt scraper elements wear quickly when used to clean the conveyor belts formed with wire seams, i.e. as the wire seams pass around the conveyor 10 roller, they generate considerable abrasive contact with the belt scraper elements causing premature wear and frequent replacement.
Another object of the invention is to provide a belt scraper mechanism having one or more resilient belt scraper units mounted to contact the lower run of the conveyor belt at a location spaced from the conveyor roller, i.e. without counter-pressure from the conveyor roller, particularly when using seamed conveyor belts.